In recent years, buildup printed wiring boards according to B2it (Buried Bump Interconnection Technology/B-square-it) are being developed as the printed wiring boards for high-density packaging. A buildup printed wiring board according to B2it may be produced by stacking copper-foil substrates called “sheets” each having a large number of conical “bumps” formed thereon.
After the formation of the bumps on such a buildup wiring board according to B2it, a test needs to be conducted with an image pickup camera to determine whether or not each of the bumps has a predetermined shape and size and is located in a predetermined position on the sheet. To conduct such a test on the bumps, a technique of measuring the height of each protrusion formed on a work surface can be utilized, as disclosed in Patent Reference 1.
The sheets may have a large standardized size, and some sheets are larger than the image size that can be captured by a camera. To conduct a test on such sheets with high precision in a short period of time, a number of cameras are required. For example, in a case where each sheet is 1000 mm in the test width direction, and the image capture width that can be captured by one camera is 20 mm, fifty cameras are required to conduct a test on one sheet.
To counter this problem, the applicant of this application filed an application for a patent on a method for conducting a test on a large-size test object with a minimum number of CCD cameras (Patent Reference 2).
Meanwhile, in the case of test objects such as the above-mentioned buildup printed wiring boards, it is essential to conduct a test to determine whether each of the bumps has a predetermined shape and is located in a predetermined position with high precision. Therefore, it is necessary to perform precise positioning (or to establish alignment) between the position of the camera and the position of the sheet having the bumps formed thereon.    Patent Reference 1: Japanese Patent Application Publication No. 2005-61953    Patent Reference 2: Japanese Patent Application Publication No. 2006-1553605